Method and apparatus for processing shaving like materials



METHOD AND APPARATUS FOR PROCESSING SHAVING LIKE MATERIALS Filed April 27, 1960 March 27, 1962 J. E. FLEISSNER 2 Sheets-$heet 1 m A I M W yv/Awwwld si 2 E W mw a w A A a L Illll 7 LIL. Q a. a Q 3 r .7 mt @N March 27, 1962 J. E. FLEISSNER 3,027,006

METHOD AND APPARATUS FOR PROCESSING SHAVING LIKE MATERIALS Filed April 27, 1960 2 Sheets-$haet 2 Jn van for: Ja'hnmv Fq/MHNJ F/EI-HNFI' 6. 70 r IVE VS U ited States Patent 3,027,006 METHOD AND APPARATUS FOR PROCESSING SHAVING LIKE MATERIALS Johann Edmund Fleissner, Egelsbach, Frankfurt am Main, Germany, assignor to Fleissner Gesellschaft mi! beschraenkter Haftung, Frankfurt am Main, Germany, a German company Filed Apr. 27, 1960, Ser. No. 31,202 Claims priority, application Germany May 14, 1959 2 Claims. (Cl. 20911) The present invention relates to a method and to apparatus for processing shaving-like materials, such as longfibred wood shavings and the like for use in the manufacture of pressed chip-board sheets and the like.

It is an object of the invention to provide for the drying of such shaving-like material in as economical a manner as possible and to improve considerably, by comparison with known processes, the quality of such shavinglike material as it is delivered for subsequent use.

In carrying out the method according to the invention, wood shavings or other shaving-like materials to be processed, the processing including a drying operation, are shaken and thereby at least partially freed from dust before being dried. After having been dried, the material may be further shaken, thereby to remove further dust.

By shaking the material before it is dried, dust (which word is to be construed herein as including pieces of the material which are so small as to be useless, or at least undesirably small, for the purpose to which the material is destined) is removed in amounts which may, in particular cases, be as high as 30% of the total weight of the material which is shaken; and since the material is dried only after the removal of dust considerable saving is achieved of the amount of drying required, e.g. of the amount of energy which may be supplied as heat during the drying. Further, the dust which has been removed cannot block or foul the drying means and any heating units included therein. In view of these factors the drying means is used more efficiently and thus, for a given handling capacity, can be made smaller and less expensive.

Conveniently, the material to be fed to the drying means is shaken by means of a sieve having an upper surface which supports the material whilst allowing dust to fall down therefrom during shaking; and due to the shaking the material is spread on the sieve, and conveyed therefrom to the drying means, in a layer of uniform thickness which is also advantageous.

Preferably, in carrying out the invention, the said sieve is shaken simultaneously in directions normal and parallel respectively to its upper surface and the shaking sieve thus serves both to shake the material and to convey it to the drying means. Preferably again, both the amplitude and the frequency of the shaking of the sieve are adjustable, so that both the degree of dust separation and the rate of feed of material, uniformly distributed in a layer of uniform thickness, to the drying means can be controlled. Preferably, also, the sieve is removable, so that it may be replaced by a difierent sieve of different mesh size which further serves to control the degree of dust extraction.

The drying means preferably comprises one or more sieve drums on to which the material is passed, means for rotating the sieve drums, a housing which encloses the sieve drums, and means for extracting air from within the sieve drums and returning it to the exteriors thereof, inducing a flow of air into each sieve drum from within the housing to hold the material on the sieve drums and to dry it. In such drying means, the cylindrical peripheral surfaces of the sieve drums are in the form of fine mesh sieves, on which the material to be dried is "ice firmly held, as the sieve drums rotate, by the air flow due to the suction. Because of the prior dust removal, the likelihood of the mesh of the drum sieves becoming blocked or fouled by dust, which would increase the resistance to air circulation and impair the operation of the drying unit, is much reduced; and the material, for example long-fibred wood shavings, lies freely and in a random arrangement on the sieve drum surfaces in a sufiiciently open manner to allow the air to circulate through the sieve drum surfaces. Also, the dust which has been removed is thereby prevented from blocking or fouling the fan means and heating elements which are preferably provided in the path of the circulating air.

The drying unit may be provided, in known manner, with several sequentially adjacent sieve drums, the material being passed from sieve drum to sieve drum by controlling the parts thereof at which the suction is effective. For this purpose, each sieve drum is provided with an internal cover plate which covers the part of the peripheral surface thereof on which the material is not to be held. The wood shavings or other materials are sucked on to the first sieve drum and rotated therewith until adjacent the next sieve drum when they are released from the first sieve drum and sucked on to the next, this transfer continuing until by the pneumatic action of the fans they are blown off the last drum, preferably on to a chute from which they pass to a further shaking means. It may often be possible, after the material has been dried, thus to remove further dust in amounts up to about 10% of the original weight of the material. This further shaking means may conveniently be similar to that described above, by which the material is shaken before being fed to the drying means.

The drives for the sieve drums and the fan means may be provided with means for infinitely variable speed adjustment, to give infinitely variable adjustment of the drying effect.

The said shaking means and the said further shaking means may be provided respectively immediately before and immediately after the drying means, but it is within the scope of the invention to interpose a conveyor belt or the like between either one or other and the drying means.

By the use of the invention, an extremely economical and space-saving means of drying shaving-like material such as wood shavings is obtained. For example, if 30% of the original material is removed as dust by the first shaking, 70% is passed through the drying unit, after which a further 10% may be removed by the further shaking, so that 60% of the original material is available for subsequent use. Apart from the fact that less than 15% of the material which actually passed through the drying unit is lost, as compared with a much higher proportion if no dust is removed before drying, the eventual 60% of the original material which is obtained is of much higher quality than when processed by known methods for, for example, processing wood shavings for. chip-board sheets. By using the invention, approximately to of the total dust in the original material may be removed, and no further separate process for the removal of dust is necessary.

In order that the invention may be fully understood, a preferred embodiment of apparatus in accordance with the invention is described below with reference to the accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view of apparatus for processing wood shavings, and

FIGURE 2 is a transverse section of the apparatus taken on the line AB of FIGURE 1.

As shown in the drawings, the apparatus comprises drying means enclosed in a housing 11, at opposite ends of which are positioned shaking means which includes a sieve 12 and, respectively, further shaking means which includes a further sieve 13. Above an upper surface of the sieve 12, at its end remote from the housing 11, is disposed a hopper 14 containing wood shavings which are supported on the upper surface of the sieve 12. Be sides the sieve 12, the shaking means, which also serves as conveying means as will be explained, comprises a connecting rod 15 connecting the sieve 12 to an eccentric 16 which is rotated by an electric motor. The sieve 12- is resiliently supported, and, as the eccentric 16 is rotated by the motor, is shaken simultaneously normal and parallel (in the direction towards and away from the housing 11) to its upper surface. The effect of this shaking is both to shake th shavings supported on the upper surface of the sieve 12 and to convey them along the sieve 12 to the housing 11, which is provided with an aperture through which they pass. The eccentricity of the eccentric 16 is adjustable, as is its speed of revolution, so that both the amplitude and the frequency of the shaking of the sieve 12 are adjustable. The shaking is effective to separate from the material dust which falls through the sieve 12 and collects below, in amounts up to 30% of the total amount of shavings. The sieve 12 is removable and replaceable by different sieves having different mesh sizes, according to the nature of the material to be processed.

The shaking action is also effective to spread the shavings and feed them as a layer 30 of uniform thickness to the drying unit.

Within the housing 11, the drying means comprises two sieve drums 17 and 18, each having its peripheral cylindrical surface in the form of a fine mesh. The axes of the two sieve drums are parallel and in a common horizontal plane, and each sieve drum is provided with an inner cover plate 19 or 20, each covering the part of the peripheral surface of the respective sieve drums which is on one side of the said plane, and leaving the other half uncovered. The cover plates 19 and .20 are on opposite sides of the said plane, being respectively above and below the plane.

Each of the sieve drums 17 and 18 is rotatable about its axis by means of a motor and an infinitely variable gear, and as shown in FIGURE 2, the sieve drum 13 is mounted on a shaft 21 which is rotated by its motor through the infinitely variable gear 22. Coaxial with the sieve drum 18, at one end thereof, is mounted a fan 23 which is driven by a motor 24 through an infinitely variable gear. The fan 23 sucks air from within the sieve drum 18, and the air is then returned after passing over heaters 25 and through guides 26, to the exterior of the drum 18 within the housing 11. Similar fan means is provided for the sieve drum 17, and thus for both sieve drums there is induced a flow of air which holds material on the sieve drum surfaces firmly in place.

The wood shavings which enter the housing 11 from the sieve 12 are sucked on to the sieve drum 17 and carried by the rotation thereof, whilst being firmly held thereon by the air flow, until they are adjacent the drum 18. On further rotation, the cover plate 19 removes the suction effect as the shavings come opposite the part of the sieve drum 18 which is not covered by the cover plate 20, and are therefore sucked off the sieve drum 17 on to the sieve drum 18, whose rotation brings them adjacent the end of the further sieve 13. At this point the cover plate again removes the suction effect, so that the wood shavings after having been dried during their passage through the drying means, fall on to the further sieve 13. The further shaking means which includes the sieve 13 also includes a connecting rod 27, eccentric 28 and motor, by means of which the further sieve is shaken, like the sieve 12, and like it with adjustable amplitude and frequency. The shaking of the further sieve 13 effects the removal of further dust, which may amount to a further 10% of the original material; the dust falls through the further sieve 13, and the shaking of the further sieve 13 serves to convey the dried material away from the drying means, allowing it to fall eventually into a truck 29 in which it is removed for subsequent use in for example, the manufacture of chip-board sheets.

Because the major part of the dust originally contained by the material is shaken out by the sieve 12, it cannot clog the mesh surfaces of the sieve drums 17 and 18; the flow of air through these surfaces, which are preferably of fine mesh, is thus unhindered and fully effective to hold the shavings in place and dry them. Furthermore, the dust which has been removed cannot be carried into circulation with the air, to foul the fans, heaters and guiding plates, and this, together with the fact that the removed dust does not have to be heated and dried, results in improved heating and drying performance of the drying means, as well as permitting a less frequent cleaning of the apparatus and consequent economy and increase in efificiency.

The described arrangement, in which material to be dried is carried on only half the circumference of each sieve drum, ensures a smooth flow of air to the sieve drums, so that relatively high air velocities (and consequent high temperatures) may be used without the occurrence of turbulence or tangential air flow over the material which would impair the uniform disposition of the material on the sieve drums.

By means of apparatus as described above, up to about or of the dust originally contained in wood shavings may be removed. The quality of the wood shavings is thereby considerably improved, since it is an advantage, in the manufacture of chip-board sheets, for example, that the shavings used should be as free as possible from dust; and the present invention enables such requirements to be met in very satisfactory manner.

What I claim is:

l. A method of preparing wood shavings for use in chip-board sheets comprising the successive steps of first shaking the dust-laden wood shavings on a sieve to remove the major portion of the dust from said shavings, passing the partially dust-freed shavings alternately under and over rotating sieve drums while drawing hot air through the shavings on the drums to dry the shavings first on one side and then on the other, and finally shaking the dried shavings removed from the drums on a screen to remove substantially all of the remaining minor portion of the dust from said dried shavings.

2. A method as in claim 1, further comprising shaking said shavings while said shavings are being conveyed onto and removed from said drums.

References Cited in the file of this patent UNITED STATES PATENTS 359,627 Parmelee Mar. 22, 1887 2,284,883 Symons June 2, 1942 2,679,316 Ruepp May 25, 1952 2,835,047 Fleissner May 20, 1958 FOREIGN PATENTS 515,010 Belgium Nov. 14, 1952 515,012 Belgium Nov. 14, 1952 

